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from __future__ import annotations

from collections.abc import Sequence
from functools import cached_property
from typing import TYPE_CHECKING, Any

from airflow.configuration import conf
from airflow.exceptions import AirflowException
from airflow.providers.amazon.aws.hooks.ec2 import EC2Hook
from airflow.providers.amazon.aws.triggers.ec2 import EC2StateSensorTrigger
from airflow.providers.amazon.aws.utils import validate_execute_complete_event
from airflow.sensors.base import BaseSensorOperator

if TYPE_CHECKING:
    from airflow.utils.context import Context


class EC2InstanceStateSensor(BaseSensorOperator):
    """
    Poll the state of the AWS EC2 instance until the instance reaches the target state.

    .. seealso::
        For more information on how to use this sensor, take a look at the guide:
        :ref:`howto/sensor:EC2InstanceStateSensor`

    :param target_state: target state of instance
    :param instance_id: id of the AWS EC2 instance
    :param region_name: (optional) aws region name associated with the client
    :param deferrable: if True, the sensor will run in deferrable mode
    """

    template_fields: Sequence[str] = ("target_state", "instance_id", "region_name")
    ui_color = "#cc8811"
    ui_fgcolor = "#ffffff"
    valid_states = ["running", "stopped", "terminated"]

    def __init__(
        self,
        *,
        target_state: str,
        instance_id: str,
        aws_conn_id: str | None = "aws_default",
        region_name: str | None = None,
        deferrable: bool = conf.getboolean("operators", "default_deferrable", fallback=False),
        **kwargs,
    ):
        if target_state not in self.valid_states:
            raise ValueError(f"Invalid target_state: {target_state}")
        super().__init__(**kwargs)
        self.target_state = target_state
        self.instance_id = instance_id
        self.aws_conn_id = aws_conn_id
        self.region_name = region_name
        self.deferrable = deferrable

    def execute(self, context: Context) -> Any:
        if self.deferrable:
            self.defer(
                trigger=EC2StateSensorTrigger(
                    instance_id=self.instance_id,
                    target_state=self.target_state,
                    aws_conn_id=self.aws_conn_id,
                    region_name=self.region_name,
                    poll_interval=int(self.poke_interval),
                ),
                method_name="execute_complete",
            )
        else:
            super().execute(context=context)

    @cached_property
    def hook(self):
        return EC2Hook(aws_conn_id=self.aws_conn_id, region_name=self.region_name)

    def poke(self, context: Context):
        instance_state = self.hook.get_instance_state(instance_id=self.instance_id)
        self.log.info("instance state: %s", instance_state)
        return instance_state == self.target_state

    def execute_complete(self, context: Context, event: dict[str, Any] | None = None) -> None:
        event = validate_execute_complete_event(event)

        if event["status"] != "success":
            raise AirflowException(f"Error: {event}")
